feat: release v0.27 unified HTTP limits and safe request shutdown

app/requests.go

@@ -0,0 +1,88 @@
+package app
+
+import (
+	"context"
+	"errors"
+	"fmt"
+	"sync"
+	"time"
+
+	"git.yuntuo.hk/k2safe/go-omni/lifecycle"
+)
+
+// Admission and completion share a lock: once stopped, no request can enter
+// between observing zero active handlers and releasing their dependencies.
+type requestDrain struct {
+	mu      sync.Mutex
+	stopped bool
+	active  map[*requestWork]struct{}
+	done    chan struct{}
+}
+
+type requestWork struct{ cancel context.CancelFunc }
+
+func (d *requestDrain) begin(ctx context.Context) (context.Context, *requestWork) {
+	d.mu.Lock()
+	defer d.mu.Unlock()
+	if d.stopped {
+		return ctx, nil
+	}
+	ctx, cancel := context.WithCancel(ctx)
+	w := &requestWork{cancel: cancel}
+	if d.active == nil {
+		d.active = make(map[*requestWork]struct{})
+	}
+	d.active[w] = struct{}{}
+	return ctx, w
+}
+
+func (d *requestDrain) end(w *requestWork) {
+	w.cancel()
+	d.mu.Lock()
+	defer d.mu.Unlock()
+	delete(d.active, w)
+	if d.stopped && len(d.active) == 0 {
+		close(d.done)
+	}
+}
+
+func (d *requestDrain) stop() {
+	d.mu.Lock()
+	defer d.mu.Unlock()
+	if d.stopped {
+		return
+	}
+	d.stopped = true
+	if len(d.active) == 0 {
+		close(d.done)
+	}
+}
+
+func (d *requestDrain) cancelAndWait(timeout time.Duration) error {
+	d.stop()
+	d.mu.Lock()
+	for w := range d.active {
+		w.cancel()
+	}
+	d.mu.Unlock()
+	timer := time.NewTimer(timeout)
+	defer timer.Stop()
+	select {
+	case <-d.done:
+		return nil
+	case <-timer.C:
+		select {
+		case <-d.done:
+			return nil
+		default:
+		}
+		return fmt.Errorf("go-omni: HTTP handlers did not finish within cancellation grace %s: %w", timeout,
+			errors.Join(context.DeadlineExceeded, lifecycle.ErrResourcesRetained))
+	}
+}
+
+// watchShutdown stops admission on the early signal without canceling accepted
+// work. The transport retains its graceful drain budget before Close cancels.
+func (a *App) watchShutdown(ctx context.Context) func() bool {
+	return context.AfterFunc(ctx, a.requests.stop)
+}